If you are discussing Social Security disability benefits based on previous work record, them I am unaware of anything that may affect their benefits.
If you are discussing SSI payments based on need, then there may be an effect on their benefits.
See the following link which discusses "Deemed Income" which is the part of the income of your spouse with whom you live, your parent(s) (or children) with whom you live, or your sponsor (if you are an alien), which is used to compute your SSI benefit amount.
If you are discussing Social Security disability benefits based on previous work record, them I am unaware of anything that may affect their benefits.
If you are discussing SSI payments based on need, then there may be an effect on their benefits.
See the following link which discusses "Deemed Income" which is the part of the income of your spouse with whom you live, your parent(s) (or children) with whom you live, or your sponsor (if you are an alien), which is used to compute your SSI benefit amount.
http://www.ssa.gov/ssi/text-income-ussi.htm